Templates are updated for efficient page-load-time and now font is referencing from bower_components rather than google api

**Templates are updated to render more efficiently:**
- Font referencing from ```google api``` is now referenced from ```bower_components```.
  - Written separate ```open-sans-normal.css``` to render the font.
  - To improve performance of loading resources, font is being called asynchronously without-blocking.
  - Using HTML5 localstorage (with fallback option) to load it more quickly.
- Static dependencies are moved to specific templates:
  - ```d3.js```, ```filesaver.js```, ```underscore.js``` moved to graph templates.
  - ```jqtree.js``` moved to ```theme.html``` and ```collection_ajax_view.html```.
- Redundant jQuery import is commented out.
- JS dependencies like ```MathJax``` are loaded asynchronously.
 - Depending on the condition, ```orgitdown``` dependencies are loaded for discussion feature.
- Added background-color to highlight currently selected tab in ```File``` app.

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**After taking this pull ```cd``` till ```manage.py``` (also where ```bower.json``` file resides) and do some bower installations with following command:**
**```bower install```**

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**Now what to check:**
- Check if every template is getting rendered properly.
- Wherever graph option is available, click on it and check if graph appears.
- Check for generation of tree graph in theme-topic hierarchy.
- Go to ```File``` app and click on any of the tab listed on L.H.S. (under *visit* and), check if they are getting highlighted.
- Go to ```Discussion``` tab in detail view. Add some replies or initiate new thread.
- Try some ```MathJax``` syntax to get rendered properly.